Flexible waveform synthesis in nr-ss

ABSTRACT

Flexible waveform synthesis is disclosed for new radio (NR) shared spectrum (NR-SS) networks. In order to accommodate variable transmission resources, a transmitter may construct an M×N grid to model a resource element (RE) map of transmission resources available to the transmitter within a shared communication channel, where M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter. The transmitter may then map the M×N grid to the RE map and puncture one or more REs associated with the subbands unavailable for transmission in the transmission resources. The transmitter may then transmit a transmission according to the unpunctured REs of the RE map.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional and claims the benefit of U.S. patent application Ser. No. 16/351,302, entitled, “FLEXIBLE WAVEFORM SYNTHESIS IN NR-SS,” filed, Mar. 12, 2019, and the benefit of U.S. Provisional Patent Application No. 62/653,246, entitled, “FLEXIBLE WAVEFORM SYNTHESIS IN NR-SS,” filed on Apr. 5, 2018, which is expressly incorporated by reference herein in its entirety.

BACKGROUND Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to flexible waveform synthesis in new radio (NR) shared spectrum (NR-SS) networks.

Background

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). Examples of multiple-access network formats include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stations or node Bs that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a transmission from the base station may encounter interference due to transmissions from neighbor base stations or from other wireless radio frequency (RF) transmitters. On the uplink, a transmission from the UE may encounter interference from uplink transmissions of other UEs communicating with the neighbor base stations or from other wireless RF transmitters. This interference may degrade performance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, the possibilities of interference and congested networks grows with more UEs accessing the long-range wireless communication networks and more short-range wireless systems being deployed in communities. Research and development continue to advance wireless technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

SUMMARY

In one aspect of the disclosure, a method of wireless communication includes constructing, by a transmitter, an M×N grid to model a resource element (RE) map of transmission resources available to the transmitter within a shared communication channel, wherein M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter operating on the shared communication channel, mapping, by the transmitter, the M×N grid to the RE map, puncturing, by the transmitter, one or more REs of the RE map associated with one or more unavailable subbands unavailable for transmission by the transmitter in the transmission resources, and transmitting, by the transmitter, a transmission according to unpunctured REs of the RE map.

In an additional aspect of the disclosure, a method of wireless communication includes detecting, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum, performing, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals, determining, by the receiver, a sequence based on the joint correlation, and decoding, by the receiver, transmission information from the sequence.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon, which when executed causes a processor to perform wireless communication. Further, the program code includes code to construct, by a transmitter, an M×N grid to model a RE map of transmission resources available to the transmitter within a shared communication channel, wherein M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter operating on the shared communication channel, code to map, by the transmitter, the M×N grid to the RE map, code to puncture, by the transmitter, one or more REs of the RE map associated with one or more unavailable subbands unavailable for transmission by the transmitter in the transmission resources, and code to transmit, by the transmitter, a transmission according to unpunctured REs of the RE map.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code which when executed causes a processor to perform wireless communication. Further, the program code includes code to detect, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum, code to perform, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals, code to determine, by the receiver, a sequence based on the joint correlation, and code to decode, by the receiver, transmission information from the sequence.

In an additional aspect of the disclosure, a system of wireless communication includes means for constructing, by a transmitter, an M×N grid to model a RE map of transmission resources available to the transmitter within a shared communication channel, wherein M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter operating on the shared communication channel, means for mapping, by the transmitter, the M×N grid to the RE map, means for puncturing, by the transmitter, one or more REs of the RE map associated with one or more unavailable subbands unavailable for transmission by the transmitter in the transmission resources, and means for transmitting, by the transmitter, a transmission according to unpunctured REs of the RE map.

In an additional aspect of the disclosure, a system of wireless communication includes means for detecting, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum, means for performing, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals, means for determining, by the receiver, a sequence based on the joint correlation, and means for decoding, by the receiver, transmission information from the sequence.

In an additional aspect of the disclosure, a system of wireless communication includes at least one processor and a memory, coupled thereto, that stores information and logic executable by the processor. Further, the processor may be configured to construct, by a transmitter, an M×N grid to model a RE map of transmission resources available to the transmitter within a shared communication channel, wherein M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter operating on the shared communication channel, to map, by the transmitter, the M×N grid to the RE map, to puncture, by the transmitter, one or more REs of the RE map associated with one or more unavailable subbands unavailable for transmission by the transmitter in the transmission resources, and to transmit, by the transmitter, a transmission according to unpunctured REs of the RE map.

In an additional aspect of the disclosure, a system of wireless communication includes at least one processor and a memory, coupled thereto, that stores information and logic executable by the processor. Further, the processor may configured to detect, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum, to perform, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals, to determine, by the receiver, a sequence based on the joint correlation, and to decode, by the receiver, transmission information from the sequence.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wireless communication system.

FIG. 2 is a block diagram illustrating a design of a base station and a UE configured according to one aspect of the present disclosure.

FIG. 3 is a block diagram illustrating a wireless communication system including base stations that use directional wireless beams.

FIG. 4 is a block diagram illustrating a base station and UEs within an NR-SS network configured according to one aspect of the present disclosure.

FIGS. 5A and 5B are block diagrams illustrating example blocks executed to implement one aspect of the present disclosure.

FIG. 6 is a block diagram illustrating a transmitter and two receivers communicating in an NR-SS network configured according to one aspect of the present disclosure.

FIG. 7 is a block diagram illustrating a base station configured according to one aspect of the present disclosure.

FIG. 8 is a block diagram illustrating a UE configured according to one aspect of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. Rather, the detailed description includes specific details for the purpose of providing a thorough understanding of the inventive subject matter. It will be apparent to those skilled in the art that these specific details are not required in every case and that, in some instances, well-known structures and components are shown in block diagram form for clarity of presentation.

This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, 5^(th) Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and Global System for Mobile Communications (GSM) are part of universal mobile telecommunication system (UMTS). In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP), and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with an ultra-high density (e.g., ˜1M nodes/km²), ultra-low complexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g., ˜10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ˜99.9999% reliability), ultra-low latency (e.g., ˜1 ms), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ˜10 Tbps/km²), extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive uplink/downlink that may be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

FIG. 1 is a block diagram illustrating 5G network 100 including various base stations and UEs configured according to aspects of the present disclosure. The 5G network 100 includes a number of base stations 105 and other network entities. A base station may be a station that communicates with the UEs and may also be referred to as an evolved node B (eNB), a next generation eNB (gNB), an access point, and the like. Each base station 105 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to this particular geographic coverage area of a base station and/or a base station subsystem serving the coverage area, depending on the context in which the term is used.

A base station may provide communication coverage for a macro cell or a small cell, such as a pico cell or a femto cell, and/or other types of cell. A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a pico cell, would generally cover a relatively smaller geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell, such as a femto cell, would also generally cover a relatively small geographic area (e.g., a home) and, in addition to unrestricted access, may also provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG), UEs for users in the home, and the like). A base station for a macro cell may be referred to as a macro base station. A base station for a small cell may be referred to as a small cell base station, a pico base station, a femto base station or a home base station. In the example shown in FIG. 1, the base stations 105 d and 105 e are regular macro base stations, while base stations 105 a-105 c are macro base stations enabled with one of 3 dimension (3D), full dimension (FD), or massive MIMO. Base stations 105 a-105 c take advantage of their higher dimension MIMO capabilities to exploit 3D beamforming in both elevation and azimuth beamforming to increase coverage and capacity. Base station 105 f is a small cell base station which may be a home node or portable access point. A base station may support one or multiple (e.g., two, three, four, and the like) cells.

The 5G network 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a terminal, a mobile station, a subscriber unit, a station, or the like. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, or the like. In one aspect, a UE may be a device that includes a Universal Integrated Circuit Card (UICC). In another aspect, a UE may be a device that does not include a UICC. In some aspects, UEs that do not include UICCs may also be referred to as internet of everything (IoE) devices. UEs 115 a-115 d are examples of mobile smart phone-type devices accessing 5G network 100 A UE may also be a machine specifically configured for connected communication, including machine type communication (MTC), enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. UEs 115 e-115 k are examples of various machines configured for communication that access 5G network 100. A UE may be able to communicate with any type of the base stations, whether macro base station, small cell, or the like. In FIG. 1, a lightning bolt (e.g., communication links) indicates wireless transmissions between a UE and a serving base station, which is a base station designated to serve the UE on the downlink and/or uplink, or desired transmission between base stations, and backhaul transmissions between base stations.

In operation at 5G network 100, base stations 105 a-105 c serve UEs 115 a and 115 b using 3D beamforming and coordinated spatial techniques, such as coordinated multipoint (CoMP) or multi-connectivity. Macro base station 105 d performs backhaul communications with base stations 105 a-105 c, as well as small cell, base station 105 f. Macro base station 105 d also transmits multicast services which are subscribed to and received by UEs 115 c and 115 d. Such multicast services may include mobile television or stream video, or may include other services for providing community information, such as weather emergencies or alerts, such as Amber alerts or gray alerts.

5G network 100 also support mission critical communications with ultra-reliable and redundant links for mission critical devices, such UE 115 e, which is a drone. Redundant communication links with UE 115 e include from macro base stations 105 d and 105 e, as well as small cell base station 105 f. Other machine type devices, such as UE 115 f (thermometer), UE 115 g (smart meter), and UE 115 h (wearable device) may communicate through 5G network 100 either directly with base stations, such as small cell base station 105 f, and macro base station 105 e, or in multi-hop configurations by communicating with another user device which relays its information to the network, such as UE 115 f communicating temperature measurement information to the smart meter, UE 115 g, which is then reported to the network through small cell base station 105 f. 5G network 100 may also provide additional network efficiency through dynamic, low-latency TDD/FDD communications, such as in a vehicle-to-vehicle (V2V) mesh network between UEs 115 i-115 k communicating with macro base station 105 e.

FIG. 2 shows a block diagram of a design of a base station 105 and a UE 115, which may be one of the base station and one of the UEs in FIG. 1. At the base station 105, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232 a through 232 t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232 a through 232 t may be transmitted via the antennas 234 a through 234 t, respectively.

At the UE 115, the antennas 252 a through 252 r may receive the downlink signals from the base station 105 and may provide received signals to the demodulators (DEMODs) 254 a through 254 r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators 254 a through 254 r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive and process data (e.g., for the PUSCH) from a data source 262 and control information (e.g., for the PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators 254 a through 254 r (e.g., for SC-FDM, etc.), and transmitted to the base station 105. At the base station 105, the uplink signals from the UE 115 may be received by the antennas 234, processed by the demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 115. The processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at the base station 105 and the UE 115, respectively. The controller/processor 240 and/or other processors and modules at the base station 105 may perform or direct the execution of various processes for the techniques described herein. The controllers/processor 280 and/or other processors and modules at the UE 115 may also perform or direct the execution of the functional blocks illustrated in FIGS. 5A and 5B, and/or other processes for the techniques described herein. The memories 242 and 282 may store data and program codes for the base station 105 and the UE 115, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Wireless communications systems operated by different network operating entities (e.g., network operators) may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (e.g., time) may be partitioned and allocated to the different network operating entities for certain types of communication.

For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

In some cases, UE 115 and base station 105 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs 115 or base stations 105 may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE 115 or base station 105 may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available. A CCA may include an energy detection procedure to determine whether there are any other active transmissions. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In 5G network 100, base stations 105 and UEs 115 may be operated by the same or different network operating entities. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In other examples, each base station 105 and UE 115 may be operated by a single network operating entity. Requiring each base station 105 and UE 115 of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

FIG. 3 illustrates an example of a timing diagram 300 for coordinated resource partitioning. The timing diagram 300 includes a superframe 305, which may represent a fixed duration of time (e.g., 20 ms). Superframe 305 may be repeated for a given communication session and may be used by a wireless system such as 5G network 100 described with reference to FIG. 1. The superframe 305 may be divided into intervals such as an acquisition interval (A-INT) 310 and an arbitration interval 315. As described in more detail below, the A-INT 310 and arbitration interval 315 may be subdivided into sub-intervals, designated for certain resource types, and allocated to different network operating entities to facilitate coordinated communications between the different network operating entities. For example, the arbitration interval 315 may be divided into a plurality of sub-intervals 320. Also, the superframe 305 may be further divided into a plurality of subframes 325 with a fixed duration (e.g., 1 ms). While timing diagram 300 illustrates three different network operating entities (e.g., Operator A, Operator B, Operator C), the number of network operating entities using the superframe 305 for coordinated communications may be greater than or fewer than the number illustrated in timing diagram 300.

The A-INT 310 may be a dedicated interval of the superframe 305 that is reserved for exclusive communications by the network operating entities. In some examples, each network operating entity may be allocated certain resources within the A-INT 310 for exclusive communications. For example, resources 330-a may be reserved for exclusive communications by Operator A, such as through base station 105 a, resources 330-b may be reserved for exclusive communications by Operator B, such as through base station 105 b, and resources 330-c may be reserved for exclusive communications by Operator C, such as through base station 105 c. Since the resources 330-a are reserved for exclusive communications by Operator A, neither Operator B nor Operator C can communicate during resources 330-a, even if Operator A chooses not to communicate during those resources. That is, access to exclusive resources is limited to the designated network operator. Similar restrictions apply to resources 330-b for Operator B and resources 330-c for Operator C. The wireless nodes of Operator A (e.g, UEs 115 or base stations 105) may communicate any information desired during their exclusive resources 330-a, such as control information or data.

When communicating over an exclusive resource, a network operating entity does not need to perform any medium sensing procedures (e.g., listen-before-talk (LBT) or clear channel assessment (CCA)) because the network operating entity knows that the resources are reserved. Because only the designated network operating entity may communicate over exclusive resources, there may be a reduced likelihood of interfering communications as compared to relying on medium sensing techniques alone (e.g., no hidden node problem). In some examples, the A-INT 310 is used to transmit control information, such as synchronization signals (e.g., SYNC signals), system information (e.g., system information blocks (SIBs)), paging information (e.g., physical broadcast channel (PBCH) messages), or random access information (e.g., random access channel (RACH) signals). In some examples, all of the wireless nodes associated with a network operating entity may transmit at the same time during their exclusive resources.

In some examples, resources may be classified as prioritized for certain network operating entities. Resources that are assigned with priority for a certain network operating entity may be referred to as a guaranteed interval (G-INT) for that network operating entity. The interval of resources used by the network operating entity during the G-INT may be referred to as a prioritized sub-interval. For example, resources 335-a may be prioritized for use by Operator A and may therefore be referred to as a G-INT for Operator A (e.g., G-INT-OpA). Similarly, resources 335-b may be prioritized for Operator B, resources 335-c may be prioritized for Operator C, resources 335-d may be prioritized for Operator A, resources 335-e may be prioritized for Operator B, and resources 335-f may be prioritized for operator C.

The various G-INT resources illustrated in FIG. 3 appear to be staggered to illustrate their association with their respective network operating entities, but these resources may all be on the same frequency bandwidth. Thus, if viewed along a time-frequency grid, the G-INT resources may appear as a contiguous line within the superframe 305. This partitioning of data may be an example of time division multiplexing (TDM). Also, when resources appear in the same sub-interval (e.g., resources 340-a and resources 335-b), these resources represent the same time resources with respect to the superframe 305 (e.g., the resources occupy the same sub-interval 320), but the resources are separately designated to illustrate that the same time resources can be classified differently for different operators.

When resources are assigned with priority for a certain network operating entity (e.g., a G-INT), that network operating entity may communicate using those resources without having to wait or perform any medium sensing procedures (e.g., LBT or CCA). For example, the wireless nodes of Operator A are free to communicate any data or control information during resources 335-a without interference from the wireless nodes of Operator B or Operator C.

A network operating entity may additionally signal to another operator that it intends to use a particular G-INT. For example, referring to resources 335-a, Operator A may signal to Operator B and Operator C that it intends to use resources 335-a. Such signaling may be referred to as an activity indication. Moreover, since Operator A has priority over resources 335-a, Operator A may be considered as a higher priority operator than both Operator B and Operator C. However, as discussed above, Operator A does not have to send signaling to the other network operating entities to ensure interference-free transmission during resources 335-a because the resources 335-a are assigned with priority to Operator A.

Similarly, a network operating entity may signal to another network operating entity that it intends not to use a particular G-INT. This signaling may also be referred to as an activity indication. For example, referring to resources 335-b, Operator B may signal to Operator A and Operator C that it intends not to use the resources 335-b for communication, even though the resources are assigned with priority to Operator B. With reference to resources 335-b, Operator B may be considered a higher priority network operating entity than Operator A and Operator C. In such cases, Operators A and C may attempt to use resources of sub-interval 320 on an opportunistic basis. Thus, from the perspective of Operator A, the sub-interval 320 that contains resources 335-b may be considered an opportunistic interval (O-INT) for Operator A (e.g., O-INT-OpA). For illustrative purposes, resources 340-a may represent the O-INT for Operator A. Also, from the perspective of Operator C, the same sub-interval 320 may represent an O-INT for Operator C with corresponding resources 340-b. Resources 340-a, 335-b, and 340-b all represent the same time resources (e.g., a particular sub-interval 320), but are identified separately to signify that the same resources may be considered as a G-INT for some network operating entities and yet as an O-INT for others.

To utilize resources on an opportunistic basis, Operator A and Operator C may perform medium-sensing procedures to check for communications on a particular channel before transmitting data. For example, if Operator B decides not to use resources 335-b (e.g., G-INT-OpB), then Operator A may use those same resources (e.g., represented by resources 340-a) by first checking the channel for interference (e.g., LBT) and then transmitting data if the channel was determined to be clear. Similarly, if Operator C wanted to access resources on an opportunistic basis during sub-interval 320 (e.g., use an O-INT represented by resources 340-b) in response to an indication that Operator B was not going to use its G-INT, Operator C may perform a medium sensing procedure and access the resources if available. In some cases, two operators (e.g., Operator A and Operator C) may attempt to access the same resources, in which case the operators may employ contention-based procedures to avoid interfering communications. The operators may also have sub-priorities assigned to them designed to determine which operator may gain access to resources if more than operator is attempting access simultaneously.

In some examples, a network operating entity may intend not to use a particular G-INT assigned to it, but may not send out an activity indication that conveys the intent not to use the resources. In such cases, for a particular sub-interval 320, lower priority operating entities may be configured to monitor the channel to determine whether a higher priority operating entity is using the resources. If a lower priority operating entity determines through LBT or similar method that a higher priority operating entity is not going to use its G-INT resources, then the lower priority operating entities may attempt to access the resources on an opportunistic basis as described above.

In some examples, access to a G-INT or O-INT may be preceded by a reservation signal (e.g., request-to-send (RTS)/clear-to-send (CTS)), and the contention window (CW) may be randomly chosen between one and the total number of operating entities.

In some examples, an operating entity may employ or be compatible with coordinated multipoint (CoMP) communications. For example an operating entity may employ CoMP and dynamic time division duplex (TDD) in a G-INT and opportunistic CoMP in an O-INT as needed.

In the example illustrated in FIG. 3, each sub-interval 320 includes a G-INT for one of Operator A, B, or C. However, in some cases, one or more sub-intervals 320 may include resources that are neither reserved for exclusive use nor reserved for prioritized use (e.g., unassigned resources). Such unassigned resources may be considered an O-INT for any network operating entity, and may be accessed on an opportunistic basis as described above.

In some examples, each subframe 325 may contain 14 symbols (e.g., 250-μs for 60 kHz tone spacing). These subframes 325 may be standalone, self-contained Interval-Cs (ITCs) or the subframes 325 may be a part of a long ITC. An ITC may be a self-contained transmission starting with a downlink transmission and ending with a uplink transmission. In some embodiments, an ITC may contain one or more subframes 325 operating contiguously upon medium occupation. In some cases, there may be a maximum of eight network operators in an A-INT 310 (e.g., with duration of 2 ms) assuming a 250-μs transmission opportunity.

Although three operators are illustrated in FIG. 3, it should be understood that fewer or more network operating entities may be configured to operate in a coordinated manner as described above. In some cases, the location of the G-INT, O-INT, or A-INT within superframe 305 for each operator is determined autonomously based on the number of network operating entities active in a system. For example, if there is only one network operating entity, each sub-interval 320 may be occupied by a G-INT for that single network operating entity, or the sub-intervals 320 may alternate between G-INTs for that network operating entity and O-INTs to allow other network operating entities to enter. If there are two network operating entities, the sub-intervals 320 may alternate between G-INTs for the first network operating entity and G-INTs for the second network operating entity. If there are three network operating entities, the G-INT and O-INTs for each network operating entity may be designed as illustrated in FIG. 3. If there are four network operating entities, the first four sub-intervals 320 may include consecutive G-INTs for the four network operating entities and the remaining two sub-intervals 320 may contain O-INTs. Similarly, if there are five network operating entities, the first five sub-intervals 320 may contain consecutive G-INTs for the five network operating entities and the remaining sub-interval 320 may contain an O-INT. If there are six network operating entities, all six sub-intervals 320 may include consecutive G-INTs for each network operating entity. It should be understood that these examples are for illustrative purposes only and that other autonomously determined interval allocations may be used.

It should be understood that the coordination framework described with reference to FIG. 3 is for illustration purposes only. For example, the duration of superframe 305 may be more or less than 20 ms. Also, the number, duration, and location of sub-intervals 320 and subframes 325 may differ from the configuration illustrated. Also, the types of resource designations (e.g., exclusive, prioritized, unassigned) may differ or include more or less sub-designations.

In NR-SS networks, the availability of time/frequency resources is uncertain. For example, in unlicensed deployments, the communication spectrum may be shared by multiple users each competing for access. In order to achieve a more fair co-existence, the multiple users access the medium via the rules of a listen before talk (LBT) procedure. With each such user, the UEs may have various different radio frequency (RF) capabilities. High-end UE categories can support a larger bandwidth than lower UE categories. Moreover, within the same UE category, different bandwidth part (BWP) configurations are allowed in NR. With the larger system bandwidths available in NR networks, UEs may be configured to communicate using a portion of the overall system bandwidth, i.e., a BWP. Additionally, the interference profile for each UE can be different from each other and from that of the serving base station. One or more subbands can be jammed or subject to high interference by different local interferers. Accordingly, a flexible waveform synthesis may be desirable for NR-SS networks to adapt to the availability of resources, to accommodate different bandwidth capabilities, and to be robust against interference varying based on time/space.

FIG. 4 is a block diagram illustrating a base station 105 a and UEs 115 a and 115 b within an NR-SS network configured according to one aspect of the present disclosure. Each of the network entities (base station 105 a, UE 115 a, UE 115 b) may have different local interferers or different coverage availability that changes the accessibility of the communication channel as seen by each entity. For example, at base station 105 a the communication spectrum 400 identifies subbands 1, 4, and 6 as unavailable for transmission. The unavailability may be due to various different reasons, such as local interferers, coordinated interference management, geographic RF characteristics, and the like. Base station 105 a serves UEs 115 a and 115 b. However, the same RF communication spectrum at base station 105 a as seen by UEs 115 a and 115 b may appear different. For UE 115 a communication spectrum 401 identifies subbands 1 and 4-7 as unavailable, while, at UE 115 b, communication spectrum 402 identifies subbands 1 and 4-6 as unavailable. Thus, for any transmission that base station 105 a transmits on subbands 5 and 7, UE 115 b would only potentially receive the transmission on subband 7, while UE 115 a would not receive any of such transmissions.

Various aspects of the present disclosure are directed to generation and reception of a flexible waveform for NR-SS physical channels and signals. The disclosed aspects may be applied for various different signals, such as multi-band primary synchronization signals (PSS)/secondary synchronization signals (SSS), spreading sequences for small data payload, discovery reference signals (DRS), acknowledgement signals (ACK/NACK), short PUCCH signals, scheduling requests, and the like.

In this example illustrated in FIG. 4, the resource element (RE) map is denoted by a 6×7 grid (communication spectra 400-402). At the transmitter side (base station 105 a), four out of the seven subbands are available, while at the first receiver (UE 115 a) side, two out of the seven subbands are available, and at the second receiver (UE 115 b)) side, three out of the seven subbands are available. The transmitter, here base station 105 a, will transmit the flexible NR-SS waveform according to communication spectrum 400, while the receivers, UEs 115 a and 115 b, may receive part of the transmitted waveform when communication spectra 401 and 402 differ from communication spectrum 400. With the flexible NR-SS waveform, UEs 115 a and 115 b can still recover the transmitted signal based on the “partial” waveform received via their respective communication spectra 401-402. Performance of the reception may be scalable based on the differences of the resource map.

FIG. 5A is a block diagram illustrating example blocks executed by a transmitter to implement one aspect of the present disclosure. A transmitter of the example aspect may include either a base station or a UE, depending on the data and network entity for transmission. When operating according to a base station, the example blocks may also be described with respect to base station 105 as illustrated in FIG. 7. FIG. 7 is a block diagram illustrating base station 105 configured according to one aspect of the present disclosure. Base station 105 includes the structure, hardware, and components as illustrated for base station 105 of FIG. 2. For example, base station 105 includes controller/processor 240, which operates to execute logic or computer instructions stored in memory 242, as well as controlling the components of base station 105 105 that provide the features and functionality of base station 105 105. Base station 105, under control of controller/processor 240, transmits and receives signals via wireless radios 700 a-t and antennas 234 a-t. Wireless radios 700 a-t includes various components and hardware, as illustrated in FIG. 2 for base station 105 105, including modulator/demodulators 232 a-t, MIMO detector 236, receive processor 238, transmit processor 220, and TX MIMO processor 230.

When operating according to a UE, the example blocks will also be described with respect to UE 115 as illustrated in FIG. 8. FIG. 8 is a block diagram illustrating UE 115 configured according to one aspect of the present disclosure. UE 115 includes the structure, hardware, and components as illustrated for UE 115 of FIG. 2. For example, UE 115 includes controller/processor 280, which operates to execute logic or computer instructions stored in memory 282, as well as controlling the components of UE 115 that provide the features and functionality of UE 115. UE 115, under control of controller/processor 280, transmits and receives signals via wireless radios 800 a-r and antennas 252 a-r. Wireless radios 800 a-r includes various components and hardware, as illustrated in FIG. 2 for UE 115, including modulator/demodulators 254 a-r, MIMO detector 256, receive processor 258, transmit processor 264, and TX MIMO processor 266.

At block 500, a transmitter constructs an M×N grid to model a RE map of transmission resources available to the transmitter within a shared communication channel. For the modeled grid, M corresponds to a number of symbols for a scheduled physical signal and N corresponds to a number of tones of a transmission bandwidth for the transmitter operating on the shared communication channel. The transmitter may be any network entity that has data for transmission (e.g., base station for downlink transmission, UE for uplink transmission). When operated as a base station, such as base station 105, sequence generator 701, stored in memory 242, under control of controller/processor 240, is executed, and the execution environment of sequence generator 701 may generate the constant amplitude zero autocorrelation (CAZAC)-type and chirp sequences, as described in greater detail below. Base station 105 may then execute modeling grid generator 702, stored in memory 242. The execution environment of modeling grid generator 702 concatenates the generated sequences into the M×N grid to model the RE map. When operated as a UE, such as UE 115, similar actions are taken with regard to sequence generator 804 and modeling grid generator 805, stored in memory 282, under control of controller/processor 280.

At block 501, the transmitter maps the M×N grid to the RE map. Before beginning transmissions, the transmitter first maps the modeled grid to the actual RE map of the communication channel. When operated as a base station, base station 105 executes resource mapping logic 703, stored in memory 242. The execution environment of resource mapping logic 703 maps the M×N grid to the RE map for the transmission resources available to base station 105. When operated as a UE, UE 115 performs similar actions with regard to resource mapping logic 806, stored in memory 282.

At block 502, the transmitter punctures one or more REs of the RE map associated with one or more unavailable subbands unavailable for transmission by the transmitter in the transmission resources. The RE map maps over the entire available set of resources of the communication channel. However, because some of the subbands are unavailable for transmission, the transmitter will first puncture the REs of the RE map that correspond to the spectrum hold created by the unavailable subbands. When operated as a base station, base station 105, under control of controller/processor 240, executes puncturing logic 704, stored in memory 242. The execution environment of puncturing logic 704 provides puncturing of the RE map corresponding to the unavailable subbands within the transmission resources. When operated as a UE, UE 115 performs similar actions with regard to puncturing logic 807, stored in memory 282.

At block 503, the transmitter transmits a transmission according to unpunctured REs of the RE map. Once the RE map has been punctured to accommodate the unavailable resources, the transmitter may transmit the signals on the unpunctured REs of the RE map. When operated as a base station, base station 105, after preparing the punctured RE map, may then transmit the data stored at downlink data 705 in memory 242. The data is transmitted according to the unpuctured resource elements of the RE map via wireless radios 700 a-t and antennas 234 a-t. When operated as a UE, UE 115 performs similar actions with regard to the data stored at uplink data 808 in memory 282 and transmitting the data via wireless radios 800 a-r and antennas 252 a-r.

The resource map (e.g. time-frequency grid used by NR-SS OFDM waveform) may be modeled, as noted above, by a two-dimensional grid of size M by N, where M is the number of OFDM symbols pre-configured for the physical signal, which is upper bounded by the length of the transmission opportunity (TxOP), and N is the number of tones spanned by the largest transmission bandwidth for opportunistic spectrum sharing. Because of its autocorrelation properties, a constant amplitude zero autocorrelation (CAZAC)-type sequence S_(M) of length M, is used to generate the signal for the flexible NR-SS waveform. The sequence, S_(M) is given by

S _(M) ≙[s(0) s(1) . . . s(M−1)]  (1)

Consider K chirp sequences of length N/K, which is given by

$\begin{matrix} {{C_{k}\overset{\Delta}{=}\begin{bmatrix} {c\left( {k,0} \right)} & {c\left( {k,1} \right)} & \ldots & {c\left( {k,{\frac{N}{K} - 1}} \right)} \end{bmatrix}},{{\ldots \mspace{11mu} 0} \leq k \leq {\frac{N}{K} - 1}}} & (2) \end{matrix}$

K may be selected based on various considerations. For example, K may be selected as equivalent to the number subcarriers within a subband, such that N is divisible by K. Construct a two dimensional array of size M by N by concatenating S_(M) and

$\left\{ {C_{k},{0 \leq k \leq {\frac{N}{K} - 1}}} \right\},$

such as

$\begin{matrix} {{\alpha_{m,n}\overset{\Delta}{=}{{s(m)}{c\left( {{{floor}\left( \frac{nK}{N} \right)},{{mod}\left( {n,\frac{N}{K}} \right)}} \right)}}},{0 \leq m \leq {M - 1}},{0 \leq n \leq {N - 1}}} & (3) \end{matrix}$

The transmitter punctures the columns of [α_(m,n)] corresponding to the unavailable subbands. To generate the waveform, the transmitter would then map the punctured [α_(m,n)] to the resource grid of same size.

FIG. 5B is a block diagram illustrating example blocks executed by a receiver to implement one aspect of the present disclosure. A receiver of the example aspect may include either a base station or a UE, depending on the data and network entity receiving transmitted data. When operating according to a base station, the example blocks may also be described with respect to base station 105, as illustrated in FIG. 7, and when operating according to a UE, the example blocks may also be described with respect to UE 115, as illustrated in FIG. 8.

On the receiver side, the receiver may monitor for the flexible NR-SS waveform over the communication channel. At block 504, a receiver detects a plurality of signals on a plurality of subbands over a communication channel. When operated as a UE, UE 115 detects signals received over antennas 252 a-r and wireless radios 800 a-r. When operated as a base station, base station 105 performs similar receiving actions over antennas 234 a-t and wireless radios 700 a-t.

At block 505, the receiver performs joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals. The receiver conducts joint correlation over time and frequency for each successful signal and each successive subband. When operated as a UE, UE 115, under control of controller/processor 280 activates correlators 801 to perform the joint time/frequency domain correlation of each successive signal. When operated as a base station, base station 105 would perform similar correlation via correlators 706. The receiver may perform the correlation using a number of correlator banks per subband. The number may be determined by the receiver based on the receivers bandwidth capabilities. For example, the more bandwidth the receiver is capable of handling, the higher number of correlator banks may be used. Thus, correlators 706 and 801 may include such numbers of correlator banks per subband.

At block 506, the receiver determines a sequence based on the joint correlation. The joint correlation allows the receiver to detect whether the signal includes a sequence. For example, as the receiver progressively performs the correlation on each signal and each subband, it may combine the correlation metrics to improve the success at determining a sequence, in addition to improving the ability to recognize a sequence by comparing the correlation metrics from each successive subband. When operated as a UE, UE 115 executes sequence detection logic 802, stored in memory 282. The execution environment of sequence detection logic 802 uses the correlation results from correlators 801 to determine the sequence embedded into the signals. When operated as a base station, base station 105 performs similar actions with regard to correlators 706 and sequence detection logic 707, stored in memory 242.

At block 507, the receiver decodes transmission information from the sequence. Once the receiver determines the sequence embedded in the detected signal, it may decode the information encoded into the sequence by the transmitter. When operated as a UE, UE 115 executes decoder 803. The execution environment of decoder 803 allows UE 115 to decode the information contained within the sequence that was detected in the signal. When operated as a base station, base station 105 performs similar actions using decoder 708.

FIG. 6 is a block diagram illustrating a transmitter 600 and two receivers 601 and 602 communicating in an NR-SS network configured according to one aspect of the present disclosure. Transmitter 600 may be a base station, gNB, or a UE depending on the network entity that will be performing transmission of some kind of signal. Receivers 601 and 602 may also either be base stations, gNBs, or UEs depending on which type of network entity is transmitting. The various described operations of transmitters and/or receivers would apply to whichever network entity was operating as the transmitter or receiver in any given circumstance. For example, an RE map 603 as seen from transmitter 600 identifies six of the available 14 subbands that are unavailable for transmissions. Accordingly, after creating the M×N grid model and generating the CAZAC and chirp sequences that are concatenated onto the grid model, mapped to RE map 603 and then punctured for the six unavailable subbands, transmitter 600 will transmit its signal or information encoded into the sequence on the unpunctured/available REs of the communication channel.

In one example aspect, a scrambling sequence can be superimposed onto the model grid [α_(m,n)] to reduce the peak-to-average-power ratio (PAPR). Transmitter 600 would select the S_(M) and scrambling sequence as a function of “spectrum hole” location (where the six unavailable subbands are located). For example, the root index and cyclic shift of S_(M) can be mapped to a bit map, which corresponds to the subband index of the spectrum hole. Receivers 601 and 602 may conduct joint correlation in the time and frequency domains.

It should be noted that a larger time and bandwidth product may lead to better correlation behavior. However, even a partial bandwidth occupancy would preserve the time-domain correlation property of S_(M). Therefore, even with the partial bandwidth occupancy, receivers 601 and 602 may successfully decode the transmission information transmitted by transmitter 600.

The spectrum hole location can be noted as part of system information that is broadcast by the network, so that both the transmitter and receivers can know the relationship between the scrambling sequence and the model grid sequence, α. Thus, by knowing the scrambling sequence, the transmitter or receiver may know the shape or location of the spectrum hole as seen by the transmitter.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The functional blocks and modules in FIGS. 5A and 5B may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Skilled artisans will also readily recognize that the order or combination of components, methods, or interactions that are described herein are merely examples and that the components, methods, or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those illustrated and described herein.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Computer-readable storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, a connection may be properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL), then the coaxial cable, fiber optic cable, twisted pair, or DSL, are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

As used herein, including in the claims, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) or any of these in any combination thereof.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

What is claimed is:
 1. A method of wireless communication, comprising: detecting, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum; performing, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals; determining, by the receiver, a sequence based on the joint correlation; and decoding, by the receiver, transmission information from the sequence.
 2. The method of claim 1, wherein the determining the sequence includes one or more of: comparing, by the receiver, correlation metrics of the joint correlation for first signals of the plurality of signals against subsequent correlation metrics of the joint correlation for subsequent signals of the plurality of signals for the determining the sequence; and adding, by the receiver, the correlation metrics and the subsequent correlation metrics and determining the sequence based on a sum of the correlation metrics and the subsequent correlation metrics.
 3. The method of claim 1, wherein the joint correlation is performed by parallel correlator banks at a transmitter for each subband of one or more subbands of the plurality of subbands in the shared or unlicensed spectrum on which the plurality of signals is detected.
 4. The method of claim 3, further including: determining, by the receiver, a bandwidth capability of the receiver for communications over the communication channel; configuring, by the receiver, a number of correlator banks for the parallel correlator banks based on the bandwidth capability.
 5. The method of claim 1, wherein the detecting the plurality of signals is based on monitoring, by the receiver, for a flexible shared spectrum waveform.
 6. The method of claim 1, wherein the sequence includes one or more of: a constant amplitude zero autocorrelation (CAZAC) sequence, a chirp sequence.
 7. The method of claim 1, wherein the sequence is selected at a transmitter of the plurality of signals based on a plurality of pre-configured root indices and a plurality of pre-configured cyclic shifts.
 8. An apparatus configured for wireless communication, comprising: at least one processor; and a memory coupled to the at least one processor, wherein the at least one processor is configured: to detect, by a receiver, a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum; to perform, by the receiver, joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals; to determine, by the receiver, a sequence based on the joint correlation; and to decode, by the receiver, transmission information from the sequence.
 9. The apparatus of claim 8, wherein the configuration of the at least one processor determine the sequence includes configuration of the at least one processor to one or more of: compare, by the receiver, correlation metrics of the joint correlation for first signals of the plurality of signals against subsequent correlation metrics of the joint correlation for subsequent signals of the plurality of signals for the determining the sequence; and add, by the receiver, the correlation metrics and the subsequent correlation metrics and determining the sequence based on a sum of the correlation metrics and the subsequent correlation metrics.
 10. The apparatus of claim 8, wherein the joint correlation is performed by parallel correlator banks at the transmitter for each subband of one or more subbands of the plurality of subbands in the shared or unlicensed spectrum on which the plurality of signals is detected.
 11. The apparatus of claim 10, further including configuration of the at least one processor: to determine, by the receiver, a bandwidth capability of the receiver for communications over the communication channel; to configure, by the receiver, a number of correlator banks for the parallel correlator banks based on the bandwidth capability.
 12. The apparatus of claim 8, wherein the at least one processor is configured to detect the plurality of signals based on monitoring for a flexible shared spectrum waveform.
 13. The apparatus of claim 8, wherein the sequence includes one or more of: a constant amplitude zero autocorrelation (CAZAC) sequence, a chirp sequence.
 14. The method of claim 1, wherein the sequence is selected at a transmitter of the plurality of signals based on a plurality of pre-configured root indices and a plurality of pre-configured cyclic shifts.
 15. A non-transitory computer-readable medium having program code recorded thereon for adaptive waveform selection for signal transmission in a wireless communication system, the program code comprising: program code for causing one or more computers to: detect a plurality of signals on a plurality of subbands over a communication channel that is operating on shared or unlicensed spectrum; perform joint correlation over a time domain and a frequency domain of each successive signal of the plurality of signals; determine a sequence based on the joint correlation; and decode transmission information from the sequence.
 16. The non-transitory computer-readable medium of claim 15, wherein the program code causing one or more computers to determine the sequence includes program code to one or more of: compare correlation metrics of the joint correlation for first signals of the plurality of signals against subsequent correlation metrics of the joint correlation for subsequent signals of the plurality of signals for the determining the sequence; and add the correlation metrics and the subsequent correlation metrics and determining the sequence based on a sum of the correlation metrics and the subsequent correlation metrics.
 17. The non-transitory computer-readable medium of claim 15, wherein the program code comprises program code for causing one or more computers to: determine, by the receiver, a bandwidth capability of the receiver for communications over the communication channel; configure, by the receiver, a number of correlator banks for the parallel correlator banks based on the bandwidth capability.
 18. The non-transitory computer-readable medium of claim 15, wherein the sequence includes one or more of: a constant amplitude zero autocorrelation (CAZAC) sequence, a chirp sequence.
 19. The non-transitory computer-readable medium of claim 15, wherein the sequence is selected based on a plurality of pre-configured root indices and a plurality of pre-configured cyclic shifts.
 20. The non-transitory computer-readable medium of claim 15, wherein the program code causing one or more computers to detect the plurality of signals includes program code to monitor for a flexible shared spectrum waveform. 